[求助]新手求助~（关于初级的神经网络问题） [复制链接]

各位大虾，我在网上看到的教程里的一个程序段，本来想要试试看的： f-6hcd@Ca  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); xWkCP2$?P  
net.trainParam.show = 50; ho*44=j  
net.trainParam.lr = 0.05; r9!jIkILz  
net.trainParam.epochs = 300; [k~V77w 14  
net.trainParam.goal = 1e-5; WjfUbKg0  
p = [-1 -1 2 2;0 5 0 5]; =.vc={_?  
t = [-1 -1 1 1]; so[i"ZM)  
net=train(net,p,t); {}
F?eI  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 Pl|e?Np  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 E
Px_xX  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10  t~mbe  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 Q-<,+[/  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 ;r(hZ%pD  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 FPM@%U  
TRAINGD, Performance goal met. 5Ym/'eT  
a = sim(net,p) 8?ig/HSt2  
plot(p,t,p,a,'o') vZEeb j  
但是为什么老是报错： [x}]sT`#a  
??? Input argument "net" is undefined. x!6&)T?!n